Electronic mail, also commonly referred to as “email” or “e-mail”, can be an important form of communication service available on the Internet. It has been estimated that over 90% of over all email on the Internet is spam. Spam generally refers to email that is unwanted by recipients, while other email is referred to as “legitimate email.” As a result, many systems and tools have emerged that attempt to reduce the amount of spam received by a recipient.
Some systems and tools inspect the content of individual emails and selectively block email, such as by dropping (not delivering) email without notifying the sender, bouncing email back to the sender as not deliverable, or redirecting email to a recipient's spam/junk folder. The systems and tools may generate blacklists/whitelists of email server addresses and prevent delivery of any email associated with a blacklisted server while allowing email associated with non-blacklisted servers to pass through, and/or only passing through email that is associated with whitelisted servers. These spam systems and tools can be hosted by email clients residing on individual user computers and/or by Internet Service Providers (ISPs) that filter email before it is delivered to email clients.
Businesses are becoming increasingly concerned that their legitimate email may be inappropriately blocked by spam tools and therefore may not be delivered to the recipient. Legitimate email may be inappropriately blocked as spam due to overreaching spam content filters, as a result of unwitting previous sending of spam on the part of the sender, or as a result of inappropriate reputation seasoning on the part of the sender for the volume of mail they want to send. Businesses are therefore increasingly implementing deliverability monitoring as a way to measure whether their email appears to be reaching customers.
One way to monitor email deliverability is by sending seed (test) emails to seed accounts that have been setup at major ISPs. The seed accounts can then be monitored to determine how many seed emails have properly passed through the associated spam filters and arrived at which accounts. Analysis of which emails made it to which seed accounts may enable a business to identify when an ISP has blacklisted its originating address and/or when email contains content that is being blocked as spam. However, it may not be feasible to create seed accounts at a sufficiently representative number of ISPs that provide email services for desired recipients and, moreover, seed accounts may not be available at non-public ISPs (e.g., private company networks). Moreover, the particular content of the seed email may not adequately model how spam tools will treat actual email and the monitoring of seed email accounts may not identify email deliverability problems in a timely manner.